Despite the fact that we all know we should eat 4.5 cups of fruits and vegetables daily, many of us do not. Well, maybe a new study will change your mind. Researchers from Brigham and Women's Hospital, Harvard University, and the University of Wisconsin have found that people who eat more fruits and vegetables tend to be more optimistic - and other studies have found that optimistic people, aside from just having a sunnier outlook on life, tend to live longer and suffer from fewer heart-related diseases.